Field of the Invention
The present invention relates to a method for alleviating pain in a subject in need thereof, which comprises administering an effective amount of piscidin (PCD) peptide and a pharmaceutically acceptable carrier to the subject.
Description of Prior Art
Marine organisms are able to thrive in a pathogenic microbe-rich aquatic environment by virtue of their strong innate immune system, which prevents microbial invasion. Antimicrobial peptides serve as a first line of defense against invading pathogens, and are involved in modulating the host signaling mechanisms of the immune response. Previous studies have shown that several antimicrobial peptides inhibit the formation of nitric oxide by interacting with or affecting nitric oxide synthase; such peptides include caerin, cupiennin, dahlein, frenatin, and citropin. An α-helical antimicrobial peptide, named moronecidin or piscidin (PCD)-1, and is not only cationic, but also amphipathic in nature. PCD-1 exerts antimicrobial effects against fish ectoparasites, and bacterial and fungal pathogens. To the best of our knowledge, no earlier studies on the anti-nociceptive effects of antimicrobial peptides have been reported.
Chronic pain affects 1.5 billion people worldwide, and the 2009 global pain market was estimated to be over US $50 billion. Moreover, previous studies showed that about 20% of the general population suffers from chronic pain, and the prevalence of neuropathic pain is 6.9%. The detailed mechanisms of neuropathic pain remain unclear. Neuropathic pain is a widespread health problem associated with nerve injury, prolonged tissue damage, or injury to the peripheral or central nervous system (CNS); the resulting pain is the result of complex changes occurring at various levels in nociceptive pathways. Patients with neuropathic pain often develop hyperalgesia (an increased response to painful stimuli), allodynia (pain evoked by non-painful stimuli), and spontaneous pain and resistance to opioids and other analgesics, including non-steroidal anti-inflammatory drugs. The current research reported that no available drug treatments are able to relieve all neuropathic pain conditions. Therefore, therapeutic treatments of neuropathic syndromes remain challenging on account of their complex natural history, unclear aetiology, and poor response to drugs. The anti-epileptic drug gabapentin is widely used to treat neuropathic pain, and it effectively relieves allodynia, burning pain, shooting pain, and hyperesthesia. However, gabapentin may have side effects, including withdrawal following an adverse event, dizziness, somnolence, peripheral oedema, and gait disturbances. Hence, recent research into treating pain has focused on screening for safe, specific, and effective analgesic compounds from natural sources to alleviate neuropathic pain.
The relationship of neuropathic pain and PCD-1 is not studied in the previous reports.